added tabs
add fixes
Refactoring
jQuery UI tabs rework
jQuery UI tabs full rework
Refactoring
Merge branch 'upstream' into 365-bootstrap-tabs

* upstream: (122 commits)
  Refactored StringHelper.
  Line number tweak for error page
  added note about dependency to registerJsFile
  docs: Be explicitly clear about ActiveRecord::create()
  fixed AutoTimestamp example in advanced app
  \yii\rbac\DbManager::isAssigned() signature fix
  Changed the way to set timestamp for multiple attributes.
  Fixes issue #428 Allowing UniqueValidator to be used with non-AR models.
  Better exception page look.
  Removed unnecessary code from MSSQL schema.
  Hover and error line increased by 1 px.
  Error line number fix.
  Error line number fix.
  Error line number fix.
  Lift off!11 #418
  MSIE fix.
  Fixes (theoretically) #418 and #413.
  Removed echo
  RBAC DbManager fixes
  Always refetch the migration table definition.
  ...
Added dropdown widget
Tabs refactored
Added Nav widget closes #367
Added NavBar widget closes #437
Enhance Dropdown to use items as  strings. Remove string=divider rule
Comment for content
Lost array_merge()
Refactored based on comments and feedback (3rd round)
Refactored based on comments and feedback (3rd round)
Merge branch 'upstream' into 367-bootstrap-nav

* upstream:
  typo in Html helper
  Created a \yii\web\VerbFilter
  Implemented MaskedInput widget.
  Use class constants for Event declatration in ActionFiler
  Removed unused method.
  Updated requirements about yii\i18n\Formatter
  refactored numberformatting in base\Formatter
  Fixes issue #439
  Fixed typos in new Formatter classes
  Fixes issue #441: InvalidRequestException should be HttpException
  Removed breaking tests.
  Removed breaking test.
  Added "formatter" app component.
  Finished Formatter.
  formatter WIP.
  Added missing use statement.
  Fixed some wording
silly typo
another typo fix
fix phpDoc